Compounded lubricating oil



Patented Apr. 7, 1942 COMPOUNDED LUBBICATING on.

Roland F. Bergstrom, Oakland, Calif., assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application September 23, 1940, Serial No. 358,028

11 Claims. (Cl. 25233) This invention is a continuation-in-part of my copending applications Serial Nos. 286,236 and 338,238, filed July 24, 1939, and May 31, ,1940, respectively, the latter application now issued as Patent No. 2,270,577 of January 20, 1942, and

oil-soluble hydrocarbon-sulfonic acids are useful as anti-ringsticking agents in lubricating oils.

There it is shown that these salts tend to cause corrosiveness of the lubricating oil, and that this corrosiveness can be, inhibited by the addition of oxidation inhibitors. 1

In my earlier copending application Serial No. 286,236, I have shown that the corrosive properties of detergent soaps in lubricating oils can be reduced materially by the addition of an extreme pressure compound which contains at least one of the elements phosphorus, sulfur or chlorine, stably attached to the compound in such a way that it (this element) will not be liberated with sufficient ease under ordinary lubricating conditions of internal combustion engines to cause corrosion of the engine.

I have found that well-refined lubricating oils which contain oil-soluble hydrocarbon sulfonates 5 of polyvalent metals and, in addition, certain sulfurized esters of monohydric alcohols with monocarboxylic acids are particularly useful for v the lubrication of internal combustion engines, and more specifically of Diese engines. the absence of oxidation inhibitors, oils so compounded are remarkably stable and substantially non-corrosive in addition to having the valuable property of positively retarding or preventing piston ringsticking. If desired, oxidation inhibitors may, of course, be added further to improve the desirable properties of my compounded oils.

Metals suitable for my purpose are particu larly the light-weight metals Mg, Ca, Sr, Ba and Al. and the heavier Zn: However, other polyvalent metals may be used, if desired, especially those having only one oxide, or one of several oxides which is much more stable than and is not readily convertible to theothers under ordi nary lubrication conditions in internal combustionlengines. For example, {air anti-ringsticking oils may be produced with Cd, Sn, Co, Ni, etc.

Even in.

fonates of this invention are preferably of the oil-soluble type which are obtained, for example, in the treatment of relatively heavy mineral oils, preferably so-called paraffinic oils such as Pennsylvania or Mid-Continent gas oils or.

lubricating oils, with concentrated or preferably fuming sulfuric acid. In this kind of treatment, two types of sulfonic acids are produced-sovcalled green acids which are substantially oilinsoluble, and mahogany acids which are oilsoluble. It is the mahogany acids which I prefer to use for my purpose, although green acids may also yield certain oil-soluble salts which are applicable for my purpose. These acids constitute complicated mixtures of many different hydrocarbon sulfonic acids, many of which are believed to be of aromatic character, although others are probably of naphthenic and aliphatic origin. Some of them produce better anti-ringsticking salts'than'others. In order to isolate the most effective components, the oil-soluble acids or their salts may be. subjected to a fractionation by countercurrent extraction with two mutually immiscible solvents, a hydrocarbon liquid such as toluene, benzene, xylene, naphtha, kerosene, etc., and a water-soluble organic sol-- vent such as 'a lower-alcohol, glycol, glycerine, the latter preferably containing some water. The active component of the mahogany acid is concentrated in the hydrocarbon solvent. This method of separation has been described by Retailliau in U. S. Patent No. 2,158,680.

If desired, lubricating oils containing the sulfonic acid salts may also be produced by heavy acid treatment with concentrated or fuming sulfuric acid of a suitable lubricating oil, separating precipitated and suspended sludge, and neutralizing dissolved sulfonic acid with lime or other oxide or hydroxide of a suitable polyvalent metal.

Whilein general I prefer the oil-soluble petroleum sulfonates produced from so-called paraffinic crudes, those obtained from naphthenic or asphaltic crudes may also be used.

Other oil-soluble hydrocarbon sulfonic acids 7 suitable for my purpose may be produced by sulfonating alkyl aromatic hydrocarbons, such as alkyl benzenes, alkyl naphthalenes, alkyl anthracene, alkyl phenanthrenes, alkyl pic'enes, alkyl chrysenes, alkyl diphenyls, etc., provided the number of carbon atoms in the alkyl chain or chains is sufiicient to render the resulting sulionic acids and their salts soluble in hydrocar bon oil. It is desirable that at least one alkyl radical be relatively long, i. e., contain at least' aromatic hydrocarbon suitable for the produc' contain substitution radicals, such as hydroxyl,.

primary, secondary or tertiary amine; ether, sulflde, hydrosulfide, disulfide, halogen, etc., radicals which may be attached to the ring or to side chains or both. For example, excellent for my purpose are parailin was substituted naphthalene monosulfonic acids which contain a sulfonic radi- I cal attached to one ring of the naphthalene nucleus and a hydroxyl or amino radical attached to the other ring.

' that sulfate esters be absent, as they are liable to liberate sulfuric acid which'may-cause corrosion, or precipitation of at least-a portion of the metal component of the sulfonate, orboth. If neces-. 'sary, the sulfonic-a'cids may {be subjected to a hydrolyzing treatment before use in', the compounded oil, to eliminate sulfate or other harmful esters which may bepresent. :If desired, salts of two or more metals may be employed. 1

other hydrocarbons: aromatic acids such as benzoic, alkyl benzoic acids, naphthoic acids, alkyl naphthoic acids, etc. If desired,- the acid may contain an alcoholic H radical as, for example, in rlcinoleic acid, alphahydroxy phenyl acetic acid, salicyclic acid, alkyl salicyclic acids, hydroxy naphthoic acids, etc.

An ester which occurs naturally and meets my requirements is sperinfoil.

After sulfurization the ester should contain I between 1%-20% sulfur.

The amount of the sulfonate salts and the sulfurized ester may vary between fairly wide limits. Thus to retard or prevent piston ringsticking, I may use the sulfonate salt in amounts from .25%-5%, and preferably from .75%-2.5% by weight of the oil. The sulfurized ester may be used in amounts up to about by weight of the oil, and preferably from about 1%-7%.

The combination of sulfonate salts and sulfurized esters is particularly active in oils of relatively high V. I., e. g., oilshaving V. I. of 50 and higher.

The following example further illustrates my invention:

The corrosiveness of three oils containing calcium petroleum sulfonate (produced by converting a commercial mahogany soap to the corresponding salt) was determined by a test which 1 Sulfurized esters which I 'havefound to be particularly useful may beproduced by merely heating with free sulfur relatively: high-boiling other compound capable of sulfurizing, i.-e., of

introducing sulfur in non-oxidiaed'form into the esters. When using chlorine or pht'as'r'ihorus sulfldes, usually the treated esters will also contain in addition to the sulfur some chlorine or phosphorus, as the case may be. Thepresence of these elements is beneficial for my purpose, provided they are held sunlciently strongly by the treated compound so that they do not turn corrosive during use of the oil containing them under ordinary lubricating conditions as 'may occur in internal combustion engines.v

Sulfurization is facilitated if the ester is unsati urated. However, unsaturation is not essential.

It the ester is unsaturated, the unsaturation may be in the alcohol or acid portion of the ester amyl, hexyl, cyclohexyl, h'eptyl, octyl, lauryl,

cetyl oleyl, stearyl. etc., alcohols may be used. Of the large number of carboxylic acids, the following are particularly useful: fatty acids, pref- .erably those of 10-20 carbon atoms, e. g., lauric,

palmiticf oleic, linoleic, stearic. arachic, behemic, etc., acids, aromatic fatty acids such as phenyl acetic acid, phenyl propionic' acid, phenyl stearic acid; naphthenic acids such as those naturally contained in many petroleum oils; wool fat acids; acids obtained by oxidation of parailln wax or call the inertia-bearing test. This test ,is con ducted as follows: Two automobile connecting rods are mounted 'on a shaft which is machined to give a throw of one-half inch (radius) to the connecting rods. One rod is fitted with a copperlead and one with cadmium-silver bearing. An inertia load of steel discs is fastened to each connectingrod. The small end of each connecting rod is connected to a hinged link. The shaft on which the bearings are mounted is driven by a synchronous electric motor. Two fly wheels are mounted on the shaft in order to reduce vibration. An open sump is steam jacketed to provide heat and an auxiliary electrical heater,.with a variable resistance in series with the heater blade, provides additional heat and temperature control. a pump circulates the oil through the system. The sump is charged with one and three-fourths gallons of the oil to be tested; After the oil has been brought to 225? F., the pressure to the bearings is adjusted to 20 pounds per square inch and the machine brought up to the testing speed of 2450 R. P. M., which is maintained for 25 hours.

In the table below are given corrosion data in mg. loss of bearing obtained when testing crank case drainings of the several oils run for hours in a high speed Diesel engine:

Bearing weight loss after 2450 R. P. M.

I claim as my invention:

1. Lubricating oil suitable for internal combustion engines containing dissolved from .25%-% of a sulfonate salt and from 1%-10% of a sulfurized ester having at least carbon atoms combining a monohydric alcohol with a monocarboxylic acid, said sulfonate being 011- soluble, free of free acid and combining a hydrocarbon sulfonic acid with a polyvalent metal which forms an oxide that is not readily convertedto other oxides under conditions of crank case lubrication. v

2. The oil of claim 1 in which at least a portion of said salt is basic.

3. The'oil of claim 1 wherein said polyvalent metal is selected from the group consisting of Mg, Ca, Sr, Ba, Al and Zn. i

4. The oil of claim 1 which is free from sulfate esters. V

5. The oil of claim 1 wherein the content of the sulfonate soap is from .75% to 2.5%.

6. Lubricating oil suitable for internal combustion engines containing dissolved from .25-5.0% of a sulfonate salt and from 1%'-10% of a sulfurized ester having at least 10 carbon atoms and combining a monohydric alcohol with a monocarboxylic acid, said sulfonate being 011- soluble is free of free acid and combining a sulfonic acid of an alkyl aromatic compound con- 8. Lubricating oil suitable for internal combustion engines containing dissolved from 5.0% or -a sulfonate salt and from 1%-10% or asulfurized ester having at least. 10 carbon atoms and combining a monohydric alcohol with a monocarboxylic acid said sulfonate being oilsoluble. tree of free acid, and combining the petroleum sulfonic acid with a polyvalent metal which forms an'oxide that is not readily converted to other oxides under conditions of crank case lvbrication.

9. The oil of: claim 8 wherein the petroleum sulfonic acid is an oil-soluble mahogany acid.

vl0. Lubricating oil suitable for internal combustion engines containing dissolved from .25%-5.0% of a sulfonate salt and from 1%-10% of an ester having at least 10 carbon atoms combining a. monohydric alcoholwith a carboxylic' acid selected from the group consisting of fatty directly attached to an aromatic hydrocarbonnucleus, said sultonate being oil-soluble, free of taining an alkyl radical of at least 8 carbon atoms with a polyvalent metal which forms an oxide that is not readily converted to other oxides under conditions for crank case lubrication.

'7. The oil of claim 6 wherein said compound is an aromatic hydrocarbon.

free acid, and combining the petroleum sulfonic acid with a polyvalent metal which forms an oxide that is not readily converted to other oxides under conditions of crank case lubrication.

11. The oil of claim 10 wherein said ester is sperm oil.

ROLAND F. BERGSTROM. 

